The invention relates to a steering bearing assembly of a bicycle, more particularly to a steering bearing assembly for connecting a front wheel fork and handle bars to a frame of the bicycle.
2. DESCRIPTION OF THE RELATED ART
FIGS. 1 to 3 illustrate a steering bearing assembly which was disclosed in U. S. Pat. No. 5,095,770 and which is used to connect a front wheel fork and a handle bar to a bicycle frame. The steering bearing assembly includes a steerer tube 1, one end of which is connected to a fork 11 that carries the front wheel (not shown), a head tube 2 that is fixedly connected do an upper tube 21 and a down lower tube 22 of the bicycle frame, and a stem 3 that carries the handle bar (not shown).
The steerer tube 1 extends through the head tube 2 and through a connector 31 of the stem 3. In order for the steerer tube 1 to rotate relative to the head tube 2, a lower bearing assembly 42 and an upper bearing assembly 41 are mounted between the steerer tube 1 and the head tube 2. The upper bearing assembly 41 is located at an upper end of the head tube 2 and includes a first race 411 and a second race 412 which cooperating encase a plurality of ball bearings 413 therebetween. The first and second races 411, 412 are supported to rotate relative to one another by the ball bearings 413. The second race 412 is fixedly connected to the head tube 2 so that it rotates with the same. The first race 411 has an inner diameter that is greater than an outer diameter of the steerer tube 1 so that the steerer tube 1 is carried by the upper bearing assembly 41 with a clearance formed between the first race 411 and the steerer tube 1. The first race 411 has an annular contact face 414 which tapers at an angle with respect to a longitudinal axis of the steerer tube 1.
An annular compression ring 43 with a gap 44 is disposed above the first race 411 of the upper bearing assembly 41. The compression ring 43 has a horizontal face 430 and a tapered contact surface 431 which matches the contact face 414 of the first race 411 in the upper bearing assembly 41.
When all of the elements are in place, an adjuster nut 45 is threaded to an internally threaded upper end 12 of the steerer tube 1. The adjuster nut 45 has a head 46 that contacts an upper end of the connector 31 and that forces the same downward toward the steerer tube 1. Longitudinal and radial forces are exerted consequently on the compression ring 43 such that the latter is compressed against the steerer tube 1 and the first race 411 of the upper bearing assembly 41, thereby locking the compression spring 43 in place on the steerer tube 1.
Although the above-mentioned steering bearing assembly offers many advantages, it still has some drawbacks. For example, the internal threads at the upper end 12 of the steerer tube 1 can wear out due to constant vibration of the bicycle when in operation or after a long period of use. To replace the steerer tube 1, the user has to disassemble the entire assembly, such as the stem, the head tube or the like, thus inconveniencing the user.